To eliminate interrogator side-love suppression (ISLS), the ground radar site transmits the P2 signal in what radiating pattern?

To eliminate interrogator side-love suppression (ISLS), the ground radar site transmits the P2 signal in what radiating pattern?

• A. Narrow beam
• B. Directional
• C. Unidirectional
• D. Omnidirectional

Answer: (D)

Interrogator Side-Lobe Suppression (ISLS) is about avoiding energy that could be picked up from the transmitter’s side directions and cause false or suppressed responses in transponders. Transmitting the P2 signal omnidirectionally means the energy is radiated evenly in all azimuth directions, removing any favored direction. This uniform pattern prevents strong side-lobe indications in particular directions from influencing transponder responses, which helps ensure reliable interrogation across the entire surrounding airspace. If the P2 were concentrated in a narrow beam or directed pattern, side-lobes in other directions could become problematic and degrade ISLS performance.

Interrogator Side-Lobe Suppression (ISLS) is about avoiding energy that could be picked up from the transmitter’s side directions and cause false or suppressed responses in transponders. Transmitting the P2 signal omnidirectionally means the energy is radiated evenly in all azimuth directions, removing any favored direction. This uniform pattern prevents strong side-lobe indications in particular directions from influencing transponder responses, which helps ensure reliable interrogation across the entire surrounding airspace. If the P2 were concentrated in a narrow beam or directed pattern, side-lobes in other directions could become problematic and degrade ISLS performance.